背景：
前面的2篇文章MySQL ProxySQL读写分离使用初探和MySQL ProxySQL读写分离实践大致介绍了ProxySQL的使用说明，从文章的测试的例子中看到ProxySQL使用SQLITE来进行配置的持久化，以及ProxySQL是一个CPU密集型的中间价，如果CPU比较空闲，可以像MySQL一样安装多个实例的ProxySQL，充分利用资源。下面介绍下如何备份持久化的ProxySQL配置和多实例ProxySQL的创建。
多实例建立：
假设默认的实例已经装好了（6032、6033），现在需要新增一个新实例（ProxySQL2）：7032，7033
1，添加配置文件：
cp /etc/proxysql.cnf /etc/proxysql2.cnf
2，修改配置文件：修改3行
datadir="/var/lib/proxysql2" ... ... mysql_ifaces="127.0.0.1:7032;/tmp/proxysql_admin2.sock" ... ... interfaces="0.0.0.0:7033;/tmp/proxysql2.sock" ...
3，添加启动文件：
cp /etc/init.d/proxysql /etc/init.d/proxysql2
4，修改启动文件：
OLDDATADIR="/var/run/proxysql2" DATADIR="/var/lib/proxysql2" OPTS="-c /etc/proxysql2.cnf -D $DATADIR" 修改成新的启动 sudo -u proxysql /usr/bin/proxysql2 $OPTS 修改2行： for i in `pgrep proxysql` ; do 替换为： for i in `pidof proxysql2` ; do 最后修改一些输出： 把echo输出的proxysql改成proxysql2
5，复制执行文件（懒的修改脚本了，直接复制新起一个执行文件...）：
cp /usr/bin/proxysql /usr/bin/proxysql2
这里需要注意的是：需要修改默认实例的启动文件（/etc/init.d/proxysql）
修改2行：
for i in `pgrep proxysql` ; do
替换为：
for i in `pidof proxysql` ; do
即把pgrep改成pidof，这是因为通过pgrep找到了所有的proxysql实例的进程号，会引起误操作，单实例ProxySQL可以不需要考虑。
6，修改权限：
chown -R proxysql.proxysql proxysql2.cnf chown -R proxysql.proxysql proxysql2/
7，开启实例：
root@dbproxy:/var/lib# /etc/init.d/proxysql2 start Starting ProxySQL2: DONE! root@dbproxy:/var/lib# ps -ef| grep proxy proxysql 5324 1 0 May27 ? 00:00:00 /usr/bin/proxysql -c /etc/proxysql.cnf -D /var/lib/proxysql proxysql 5325 5324 0 May27 ? 00:20:29 /usr/bin/proxysql -c /etc/proxysql.cnf -D /var/lib/proxysql proxysql 6877 1 0 17:19 ? 00:00:00 /usr/bin/proxysql2 -c /etc/proxysql2.cnf -D /var/lib/proxysql2 proxysql 6878 6877 0 17:19 ? 00:00:00 /usr/bin/proxysql2 -c /etc/proxysql2.cnf -D /var/lib/proxysql2
查看端口信息：
root@dbproxy2:/var/lib# netstat -nltp Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 127.0.0.1:6032 0.0.0.0:* LISTEN 5325/proxysql tcp 0 0 0.0.0.0:6033 0.0.0.0:* LISTEN 5325/proxysql tcp 0 0 0.0.0.0:6033 0.0.0.0:* LISTEN 5325/proxysql tcp 0 0 0.0.0.0:6033 0.0.0.0:* LISTEN 5325/proxysql tcp 0 0 0.0.0.0:6033 0.0.0.0:* LISTEN 5325/proxysql tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 1773/sshd tcp 0 0 127.0.0.1:7032 0.0.0.0:* LISTEN 6878/proxysql2 tcp 0 0 0.0.0.0:7033 0.0.0.0:* LISTEN 6878/proxysql2 tcp 0 0 0.0.0.0:7033 0.0.0.0:* LISTEN 6878/proxysql2 tcp 0 0 0.0.0.0:7033 0.0.0.0:* LISTEN 6878/proxysql2 tcp 0 0 0.0.0.0:7033 0.0.0.0:* LISTEN 6878/proxysql2 tcp6 0 0 :::22 :::* LISTEN 1773/sshd
8：完成
root@dbproxy:/var/lib/proxysql2# /etc/init.d/proxysql2 stop Shutting down ProxySQL2: DONE! root@dbproxy:/var/lib/proxysql2# /etc/init.d/proxysql2 start Starting ProxySQL2: DONE! root@dbproxy:/var/lib/proxysql2# /etc/init.d/proxysql2 status ProxySQL2 is running (9164).
root@dbproxy2:/var/lib/proxysql2# mysql -uadmin -padmin -h127.0.0.1 -P7032 Warning: Using a password on the command line interface can be insecure. Welcome to the MySQL monitor. Commands end with ; or g. Your MySQL connection id is 1 Server version: 5.5.30 (ProxySQL Admin Module) Copyright (c) 2009-2017 Percona LLC and/or its affiliates Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or 'h' for help. Type 'c' to clear the current input statement. admin@127.0.0.1 : (none) 05:50:40>select * from mysql_servers; Empty set (0.00 sec) admin@127.0.0.1 : (none) 05:50:42>
到此，多实例已经建立成功，接着说明下如何对持久化的配置进行备份。
持久化配置备份
上面已经提到，ProxySQL的持久化是通过SQLITE实现的，对于备份就是对SQLITE的备份，关于如何使用SQLITE可以查看官方文档和SQLite教程。这里大致的说明下sqlite以 SQL 文本格式转储数据。
1：先到指定的数据db目录
root@dbproxy:/var/lib/proxysql# ls -lh -rw------- 1 proxysql proxysql 33K May 31 17:44 proxysql.db -rw------- 1 proxysql proxysql 142K May 31 17:44 proxysql.log -rw-r--r-- 1 proxysql proxysql 5 May 31 17:44 proxysql.pid
2：备份，执行.dump
root@dbproxy:/var/lib/proxysql# sqlite3 proxysql.db .dump > /home/dxy/proxysql.sql
3，还原，若还原到另一个ProxySQL（上面安装的实例proxysql2）中，先保证目标proxysql.db文件不存在(需要关闭ProxySQL，删除数据目录里的所有文件）再执行：
root@dbproxy:~# /etc/init.d/proxysql2 stop Shutting down ProxySQL2: DONE! root@dbproxy:/var/lib/proxysql2# ls -lh total 0
在目标实例目录中执行：
root@dbproxy:/var/lib/proxysql2# sqlite3 proxysql.db < /home/dxy/proxysql.sql root@dbproxy:/var/lib/proxysql2# ls -lh total 32K -rw-r--r-- 1 root root 32K May 31 18:17 proxysql.db
开启实例：
root@dbproxy:/var/lib/proxysql2# /etc/init.d/proxysql2 start Starting ProxySQL: DONE! root@dbproxy:/var/lib/proxysql2# ls -lh total 60K -rw-r--r-- 1 root root 32K May 31 18:17 proxysql.db -rw------- 1 proxysql proxysql 21K May 31 18:20 proxysql.log -rw-r--r-- 1 proxysql proxysql 5 May 31 18:20 proxysql.pid #修改权限 root@dbproxy:/var/lib/proxysql2# chown -R proxysql.proxysql proxysql.db
说明：如果备份的实例和还原的实例使用的端口全部一致，则直接开启ProxySQL就可以用了。但本文的测试备份的实例的端口是6032和6033，还原的目标实例端口是7032和7033，即使还原了也不能使用，所以需要修改db文件，用sqlite连接修改：
#连接 root@dbproxy:/var/lib/proxysql2# sqlite3 proxysql.db #修改显示 sqlite> .header on sqlite> .mode column #查看需要更新的变量 sqlite> select * from global_variables; ... admin-mysql_ifaces 127.0.0.1:6032 ... mysql-interfaces 0.0.0.0:6033;/ #更新 sqlite> update global_variables set variable_value='127.0.0.1:7032' where variable_name = 'admin-mysql_ifaces'; sqlite> update global_variables set variable_value='0.0.0.0:7033;/' where variable_name = 'mysql-interfaces';
上面操作完成之后，再开启ProxySQL验证：
root@dbproxy:/var/lib/proxysql2# /etc/init.d/proxysql2 start Starting ProxySQL2: DONE! oot@dbproxy2:/var/lib/proxysql2# mysql -uadmin -padmin -h127.0.0.1 -P7032 Warning: Using a password on the command line interface can be insecure. Welcome to the MySQL monitor. Commands end with ; or g. Your MySQL connection id is 2 Server version: 5.5.30 (ProxySQL Admin Module) Copyright (c) 2009-2017 Percona LLC and/or its affiliates Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or 'h' for help. Type 'c' to clear the current input statement. admin@127.0.0.1 : (none) 06:40:08>select * from mysql_users; +-----------+-------------------------------------------+--------+---------+-------------------+----------------+---------------+------------------------+--------------+---------+----------+-----------------+ | username | password | active | use_ssl | default_hostgroup | default_schema | schema_locked | transaction_persistent | fast_forward | backend | frontend | max_connections | +-----------+-------------------------------------------+--------+---------+-------------------+----------------+---------------+------------------------+--------------+---------+----------+-----------------+ | abc | *1AF30A6370D8959926FC3BD6158C9C551D0DBA28 | 1 | 0 | 0 | | 0 | 1 | 0 | 1 | 1 | 10000 | | bcd | *F8258EA2FA1D7FE2B55DA522BFCC87B93CC63ADF | 1 | 0 | 0 | | 0 | 1 | 0 | 1 | 1 | 10000 | +-----------+-------------------------------------------+--------+---------+-------------------+----------------+---------------+------------------------+--------------+---------+----------+-----------------+ 2 rows in set (0.00 sec) admin@127.0.0.1 : (none) 06:40:11>select * from mysql_servers; +--------------+----------------+------+--------+--------+-------------+-----------------+---------------------+---------+----------------+-----------+ | hostgroup_id | hostname | port | status | weight | compression | max_connections | max_replication_lag | use_ssl | max_latency_ms | comment | +--------------+----------------+------+--------+--------+-------------+-----------------+---------------------+---------+----------------+-----------+ | 100 | 192.168.20.123 | 3306 | ONLINE | 1 | 0 | 1000 | 10 | 0 | 0 | ReadWrite | | 1000 | 192.168.20.12 | 3306 | ONLINE | 9 | 0 | 1000 | 10 | 0 | 0 | ReadOnly | | 1000 | 192.168.20.123 | 3306 | ONLINE | 1 | 0 | 1000 | 10 | 0 | 0 | ReadWrite | +--------------+----------------+------+--------+--------+-------------+-----------------+---------------------+---------+----------------+-----------+ 3 rows in set (0.00 sec)
从上面的结果看到，持久化备份和还原成功。注意：因为sqlite不支持远程备份，需要在本地备份好之后，再传到备份中心进行保存。
总结：
到此，关于ProxySQL的介绍告已段落，ProxySQL作者的更新还是比较勤快的，若后续有新功能和特性等，再进行补充说明，关于ProxySQL的文档请见：https://github.com/sysown/ProxySQL。